Prokaryotes: The big picture
- ‘Prokaryotes’ are not a monopheyltic group
- Kingdoms Bacteria & Archaea; each with unique traits
- most species diverse groups on Earth
- Diversity of ways of making a living
- sources of energy to make ATP
- heterotrophs
- autotrophs (photosynthesis)
- Co-evolution with the planet and other organisms
- oxygen poor to oxygen rich world
- extremeophiles (temperature, pH, salt,etc.)
- prokaryotes are most abundant organisms on Earth!





Prokaryotes first to inhabit the Earth

Prokaryotes matter: First fossils
- First TRACES of living organisms
- Graphite carbon from Canadian rocks
- Formed by ‘prokaryotes’
- ~ 3.9 billion years ago!
- Cyanobacteria form stromatolites
- undisputed fossils = 3.5 bya
- western Australia
- layers of calcium carbonate precipitated over bacterial colonies

Common ancestor of all species living today: Prokaryote


Prokaryotes are structurally diverse
- Unicellular (some colonies)
- Small
- microscopic to poppy seed


Prokaryotes do it all! (review Table 27.1)
- Sources of carbon
- autotrophs (make themselves)
- heterotrophs (get from others)
- Energy for ATP (no mitochondria)
- sunlight
- organic molecules
- inorganic molecules
- Picture: Bacteria work together
- photosynthesis and N fixation

Cell surface structures: Gram + & - bacteria

Reproduction in prokaryotes: Binary fision
- Asexual: daughter cells identical to parent
- rapid reproduction
- not sustainable!
- bad for genetic diversity
- Mutations are rare but fast reproduction
- Gene transfer occurs:
- transformation =
- transduction =

Genetic Recombination: Transformation

Prokaryotes matter


Prokaryotes matter: Cynaobacteria
- Cyanobacteria: first evidence ~2.7 bya
- aka blue-green algae
- aquatic and photosynthetic
- use chlorophyll
- Photosynthesis evolved independently in distant groups
- monophyletic or paraphyletic?
- cyanobacteria are a monophyletic group
- Eukaryotes acquired photosynthesis by engulfing cyanobacteria!

Prokaryotes matter: Great Oxygenation

Prokaryotes matters: Humans
- Prokaryotes let us breath (O2)
- Bacteria and Archaea cycle nutrients
- A small % of Bacteria cause disease
